It is not clear whether swimming is safe in patients with chronic heart failure. Ten studies examining the hemodynamic effects of acute water immersion (WI) (155 patients; average age 60 years; 86% male; mean left ventricular ejection fraction (LVEF) 29%) and 6 randomized controlled trials of rehabilitation comparing swimming with either medical treatment only (n = 3) or cycling (n = 1) or aerobic exercise (n = 2), (136 patients, average age 59 years; 84% male, mean LVEF 31%) were considered. In 7 studies of warm WI (30–35°C): heart rate (HR) fell (2% to −15%), and both cardiac output (CO) (7–37%) and stroke volume (SV) increased (13–41%). In 1 study of hot WI (41°C), systemic vascular resistance (SVR) fell (41%) and HR increased (33%). In 2 studies of cold WI (12–22°C), there were no consistent effects on HR and CO. Compared with medical management, swimming led to a greater increase in peak VO2 (7–14%) and 6 minute walk test (6MWT) (7–13%). Compared with cycle training, combined swimming and cycle training led to a greater reduction in resting HR (16%), a greater increase in resting SV (23%) and SVR (15%), but no changes in resting CO and a lesser increase in peak VO2 (6%). Compared with aerobic training, combined swimming and aerobic training lead to a reduction in resting HR (19%) and SVR (54%) and a greater increase in SV (34%), resting CO (28%), LVEF (9%), and 6MWT (70%). Although swimming appears to be safe, the studies conducted have been small, very heterogeneous, and inconclusive.